A bit much (http://www.usingenglish.com/reference/idioms/a+bit+much.html)
If something is excessive or annoying, it is a bit much.
A chain is no stronger than its weakest link (http://www.usingenglish.com/reference/idioms/a+chain+is+no+stronger+than+its+weakest+link.html)
This means that processes, organisations, etc, are vulnerable because the weakest person or part can always damage or break them.
A day late and a dollar short (http://www.usingenglish.com/reference/idioms/a+day+late+and+a+dollar+short.html)
(USA) If something is a day late and a dollar short, it is too little, too late.
A fool and his money are soon parted (http://www.usingenglish.com/reference/idioms/a+fool+and+his+money+are+soon+parted.html)
This idiom means that people who aren't careful with their money spend it quickly. 'A fool and his money are easily parted' is an alternative form of the idiom.
A fool at 40 is a fool forever (http://www.usingenglish.com/reference/idioms/a+fool+at+40+is+a+fool+forever.html)
If someone hasn't matured by the time they reach forty, they never will.
A hitch in your giddy-up (http://www.usingenglish.com/reference/idioms/a+hitch+in+your+giddy-up.html)
If you have a hitch in your giddy-up, you're not feeling well. ('A hitch in your gittie-up' is also used.)
A lick and a promise (http://www.usingenglish.com/reference/idioms/a+lick+and+a+promise.html)
If you give something a lick and a promise, you do it hurriedly, most often incompletely, intending to return to it later.
A little bird told me (http://www.usingenglish.com/reference/idioms/a+little+bird+told+me.html)
If someone doesn't want to say where they got some information from, they can say that a little bird told them.